A block copolymer refers to a copolymer containing a plurality of blocks or segments of repeating units distinct in characteristics from one another. It tends to be superior in its properties to typical random copolymers or polymer blends. For example, the block copolymer may include both of soft elastic blocks (referred to as “soft segments”) and hard crystalline blocks (referred to as “hard segments,”) and thus have good properties, such as excellent elasticity and heat resistance. More specifically, such a block copolymer has elasticity at a temperature equal to or higher than the glass transition temperature of the soft segments and shows a thermoplastic behavior at a temperature above the melting temperature, consequently with relatively good heat resistance.
For specific examples of the block copolymer, SBS (styrene-butadiene-styrene) triblock copolymers and their hydrogenated versions (e.g., SEBS) are known for their usefulness in a variety of applications since they have good characteristics regarding heat resistance and elasticity.
Recently, the use of olefin-based elastomers, which are a copolymer of ethylene/propylene and α-olefin, has been intensively under consideration. More specifically, many attempts have been made to use the olefin-based elastomers in a variety of applications, such as for use purposes as a substitute for rubber materials. For further improvement on the heat resistance of the olefin-based elastomers, there has been an attempt to use block copolymer type elastomers in place of the conventional random copolymer type olefin-based elastomers such as ethylene-α-olefin random copolymers. Furthermore, many different approaches have been considered to prepare block copolymer type olefin-based elastomers with good processability in a simple production process.